We would like to off er some comments on the updated meta-analysis on intravenous magnesium sulphate for aneurysmal subarachnoid hemorrhage [1], which was conducted by Wong and colleagues
Trang 1We would like to off er some comments on the updated
meta-analysis on intravenous magnesium sulphate for
aneurysmal subarachnoid hemorrhage [1], which was
conducted by Wong and colleagues and published in a
recent issue of Critical Care.
First, the authors did not mention a (non-blinded)
random ized placebo-controlled trial conducted by
Akdemir and colleagues and published in 2009 [2]
Although this study would probably not pass Wong and
colleagues’ method of scrutiny, we believe that it should
be mentioned alongside two other studies the authors
described but did not include in the data analysis
Second, the study by Westermaier and colleagues [3]
should not be included in the data analysis Th ese
authors, in contrast to those of the other included studies
in which magnesium was used as an add-on therapy, did
not use nimodipine in any of the included patients Wong
and colleagues exclude the study by Schmid-Elsaesser
and colleagues [4] because nimodipine was not used in
the magnesium group but omit doing the same for the
study by Westermaier and colleagues
Th ird, Figure 3 [1] shows that the number of control subjects in ‘Veyna 2002’ was 20 However, in that study, the outcome data in the control group were present for only 16 patients (4 of the 20 patients were withdrawn because study requirements were not met) [5] Accordingly, the risk ratios in Figure 3 should be adjusted Fourth, given Wong and colleagues’ defi nition of delayed cerebral ischemia, we wonder why the studies of Veyna and colleagues [5], Muroi and colleagues [6], and their own study in 2006 [7] were not included in Figure 1 [1] In the study by Veyna and colleagues [5], the outcome measure ‘clinical vaso spasm’ was defi ned as a ‘new focal neurological defi cit that could not be accounted for by other causes’ Although the time frame in which this was scored is not mentioned, this was during the patients’ stay in the intensive care unit and therefore would be clinically relevant to include in Figure 1 [1] Th e same applies to the outcome measures ‘delayed ischemic neurological defi cit’ in the study by Muroi and colleagues [6] and ‘symptomatic vasospasm’ in their own study in
2006 [7]
© 2010 BioMed Central Ltd
Intravenous magnesium in subarachnoid
hemorrhage
Wilson F Abdo*, Cornelia W Hoedemaekers and Johannes G van der Hoeven
See related research by Wong et al., http://ccforum.com/content/15/1/R52
L E T T E R
Authors’ response
George KC Wong and Wai S Poon
We thank Abdo and colleagues for their interest in our
articles [1,8] and for their comments We would like to
off er the following clarifi cations
First, it is unfortunate that the article by Akdemir and
colleagues [2] slipped through the established search
methodology for the journals Nevertheless, the authors’
results on the lack of an eff ect of magnesium sulphate
infusion on clinical outcome echoed the con clusion of
our review
Second, the study by Schmid-Elsaesser and colleagues [4] compared magnesium sulphate infusion with nimodi-pine, the latter of which has an established benefi cial
eff ect on aneurysmal subarachnoid hemorrhage Th e study by Westermaier and colleagues [3] was trickier in mention ing how their cohort of patients employed nimodi pine in the Discussion section but not in the Results section Westermaier and colleagues mentioned that they did not seek an alternative route of administration for oral tablet forms of nimodipine for intubated patients but did not mention that they would omit the nimodipine oral tablets in good-grade patients
Th is actually is the policy in some neuro surgical centers
Th e nature of the comparison between magnesium sulphate infusion with placebo infusion is also diff erent
*Correspondence: f.abdo@ic.umcn.nl
Department of Critical Care Medicine, Radboud University Nijmegen Medical
Center, Geert Grooteplein 10, PO Box 9101, 6500 HB Nijmegen, The Netherlands
Abdo et al Critical Care 2011, 15:427
http://ccforum.com/content/15/3/427
© 2011 BioMed Central Ltd
Trang 2from that of Schmid-Elsaesser and colleagues [4] Again,
the omission of the data of Westermaier and colleagues
did not alter the conclusion of the review
Th ird, Veyna and colleagues [5] exposed a problem in
the earlier study report format, in which numbers of
patients were not mentioned in each step Withdrawal
could mean just the study medications, and the patients
were assessed for intention-to-treat analysis If the four
control patients had been excluded, the result would have
been the same (Figure 1) [5,6,9]
Fourth, the new defi nition of delayed cerebral ischemia
included the subsets of patients with asymptomatic
cerebral infarction [10], which turned out to be an
important prognostic factor and which earlier studies
ignored Lastly, we would like to emphasize that the
detrimental eff ect of higher-achieved plasma magnesium
concentrations further supported the results of the
current meta-analysis [11]
Competing interests
The authors declare that they have no competing interests.
Published: 24 May 2011
References
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magnesium sulphate for aneurysmal subarachnoid hemorrhage: an
updated systemic review and meta-analysis Crit Care 2011, 15:R52.
2 Akdemir H, Kulaksizogly O, Tucer B, Menku A, Postalci L, Gunaldi O:
Magnesium sulfate therapy for cerebral vasospasm after aneurysmal
subarachnoid hemorrhage Neurosurg Q 2009, 19:35-39.
3 Westermaier T, Stetter C, Vince GH, Pham M, Tejon JP, Eriskat J, Kunze E,
Matthies C, Ernestus RI, Solymosi L, Roosen K: Prophylactic intravenous
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4 Schmid-Elsaesser R, Kunz M, Zausinger S, Prueckner S, Briegel J, Steiger HJ: Intravenous magnesium versus nimodipine in the treatment of patients with aneurysmal subarachnoid hemorrhage: a randomized study
Neurosurgery 2006, 58:1054-1065.
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aneurysmal subarachnoid hemorrhage J Neurosurg 2002, 96:510-514.
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pilot study J Neurosurg Anesthesiol 2006, 18:142-148.
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subarachnoid hemorrhage: a multi-center phase III study Stroke 2010,
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M, Rinkel GJ; MASH Study Group: Magnesium sulphate in aneurysmal
subarachnoid hemorrhage Stroke 2005, 36:1011-1015.
10 Vergouwen MD, Vermeulen M, van Gijn J, Rinkel GJ, Wijicks EF, Muizelaar JP, Mendelow AD, Juvela S, Yonas H, Terbrugge KG, Macdonald RL, Diringer MN, Broderick JP, Drier JP, Roos YB: Defi nition of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage as an outcome event in clinical trials and observation studies: proposal of a multidisciplinary research
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11 Wong GK, Poon WS, Chan MT, Boet R, Gin T, Ng SC, Zee BC: Plasma magnesium concentrations and clinical outcomes in aneurysmal subarachnoid hemorrhage patients: post-hoc analysis of Intravenous Magnesium Sulphate for Aneurysmal Subarachnoid Hemorrhage (IMASH)
Trial Stroke 2010, 41:1841-1844.
doi:10.1186/cc10221
Cite this article as: Abdo WF, et al.: Intravenous magnesium in subarachnoid
hemorrhage Critical Care 2011, 15:427.
Figure 1 Fixed-eff ects model of risk ratio for a favorable outcome at 3 months A comparison between magnesium sulphate infusion and a
placebo in patients with aneurysmal subarachnoid hemorrhage is shown CI, confi dence interval; M-H, Mantel-Haenszel.
Abdo et al Critical Care 2011, 15:427
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